1. The problem statement, all variables and given/known data Points on an elliptical orbit where the speed is equal to that on a circular orbit? 2. Relevant equations 3. The attempt at a solution I have attempted this question and my calculations show that at points on minor and major axes, the radial component of velocity is zero. Hence at these points, the velocity of an orbiter in an elliptical orbit will be equal to that on a circular orbit. Is it correct? In circular orbit, velocity is always along theta direction and r component of velocity is zero. r-component of velocity is simply time derivative of magnitude of r. So setting dr/dt equal to zero and solving the resulting equation, we can find points at which Vr is zero. Please see the attached picture. I placed origin of the coordinate system at the "centre" of the ellipse. What will happen if I move the centre of coordinate system to focus of ellipse? Will the results change?